Fuel injection nozzle



March 25, 1969 Filed June 5. 1967 T. S. CHMURA FUEL INJECTION NOZZLEATTVS.

March 25, 1969 rT. s. cHMURA FUEL INJECTION NOZZLE Filed June 5, 1967Sheet INVENTOR; Bv THEODORE s. CHMURA M M ATTYS.

United States Patent O US. Cl. 239-533 11 Claims ABSTRACT F THEDISCLOSURE A fuel injection nozzle with an elongated valve body with anoriiiced tip at one end, an elongated, spring biased needle valve in thebody, a valve guide above the needle valve engaging the upper end of thevalve and having a leak off bore leading to a leak off chamber.

A fuel injection nozzle assembly comprising an elongated valve bodyhaving a nozzle tip at one end with a plurality of spray orificestherein, an elongated needle valve mounted in an axial bore in the valvebody, spring biasing means normally urging the needle valve to a closedposition engaging the valve seat in the nozzle tip and a valve guidemember engaging between the spring biasing means and inner terminal endof the needle valve, The valve guide member has an axially extendingbore open at one end to seat against the conical inner terminal end ofthe needle valve and has a rounded head at its opposite end normallyengaging the conical face of the lower spring seat. Thus, in normaloperation the valve guide and needle valve move together as a unit. Thelower edge of the bore of the valve guide member is preferably taperedat a different angle than the conical tail of the needle valve toprovide for accurate seating of the needle valve on the valve seat.Further the valve guide member is provided with an opening or portcommunicating with the fuel leak-off chamber, which port is of a flowarea substantially equal to the total flow area of the spray orifices sothat if the valve guide member sticks in an open position and the needlevalve assumes a closed position, the charge of fuel delivered by a fuelinjection pump serving a plurality of fuel injection nozzle assemblieswill `be discharged through the port in the valve guide to the fuelleak-off passage.

The present invention relates to improvements in fuel injection nozzles.

Conventionally, fuel injection nozzle assemblies are mounted in anelongated bore in the engine cylinder head, at least one nozzle beingprovided for each cylinder of the engine and a fuel pump deliverspredetermined metered quantities of fuel to each nozzle in apredetermined firing order to supply fuel to the cylinders of theengine. In some of these fuel injection nozzle assemblies, particularlythe very been the diiiiculty of providing perfect concentricity of thevalve seat and the needle valve tip to insure tight seating ofthe valve.Tight seating of the valves in the closed position is essential for thereason that if the valve is not tightly seated, fuel dripping occursbetween injections causing carbon build up on the nozzle tip andproducing poor engine combustion and excessive exhaust smoke. One remedyto overcome this problem is to precision machine the valve seatconcentric with the valve bore. However, this increases the cost of theentire assembly considerably.

In accordance with the present invention, the above problem of valveseating is overcome by providing a two-piece valve including a valveguide member having a conical or spherical face engaging a conical orspherical inner terminal end of the needle valve, there preferably beinga small differential angle between the angle of taper long pencil type,a serious problem has fueling of the of the seat and the inner terminalend of the needle valve. By this arrangement even if there is a slightmisalignment of the nozzle seat and the valve guide, the needle valvewill still be able to seat tightly at the body seat adjacent theorifices without binding the guide member, thus minimizing sluggishvalve action.

Notwithstanding the above arrangement, it has been found that in somecases over a period of prolonged use, the conventional needle valve willstill tend to stick in an open position. Thus, Where the nozzle assemblyis one of a plurality being supplied from a single positive displacementfuel injection pump, this results in over other normally operatingvalves and eX- cessive smoke is produced. In accordance with the presentinvention, this condition is eliminated by providing a port in the valveguide member communicating with the leak-off chamber having a liow areasubstantially equal to the total flow area of the spray orifices. Bythis arrangement, if the needle valve guide member sticks in an openposition and the needle valve remains seated in a closed position,uniformity of fuel metered to the other engine cylinders will not bechanged since the precise quantity which would be passed through thespray orifice of the jammed nozzle assembly, discharges through thecontrol port in the valve guide member with the result that theremaining fuel injection nozzles operate in a normal fashion.

With the foregoing in mind, an object of the present invention is toprovide a fuel injection nozzle assembly incorporating means forinsuring self seating or centering of the needle valve.

Another object of the present invention is to provide a new and improvedfuel injection nozzle which is of relatively simplified construction andfully effective in operation.

A further object of the present invention is to provide a nozzleleak-off arrangement whereby if one of the nozzle assemblies in a groupdelivering fuel to the cylinders of an engine from a common fuelinjection pump sticks closed, the operation of the remaining nozzleswhich do not stick is not adversely affected.

These and other objects of the present invention, various features anddetails of the operation and construction thereof are hereinafter morefully set forth with reference to the accompanying drawings, wherein:

FIG. l is a transverse sectional view through a fuel injection nozzleassembly constructed in accordance with the present invention;

FIG. 2 is an enlarged sectional view of the valve guide member; and

FIG. 3 is an enlarged sectional view of another embodiment of fuelinjection nozzle asembly in accordance with the present invention.

Referirng now to the drawings and particularly to FIG. 1 thereof, `thereis illustrated a fuel injection nozzle assembly generally designated bythe numeral 10 connected through a high pressure supply line or conduit12 to one of a plurality of fuel discharge ports 14 of a fuel injectionpump 16. The fuel injection pump 16 is a conventional type and may be apositive displacement pump of the type shown in Patent Number 2,518,473issued Aug. l5, 1950. In the operation of this type pump, meteredquantities of fuel are delivered in a predetermined sequence or cycle toa plurality of fuel injection nozzles for delivering fuel to thecombustion chambers of a multi-cylinder engine. The nozzle assembly issupported in and depends from a leak-off boot 17 having a leak-off`chamber 19 communicating with an outlet opening in a leak-olf by-passline 21 which in turn may be connected back to the main fuel supply.

Considering now the structural details and arrangement of the nozzleassembly, the nozzle assembly pin comprises an elongated nozzle bodyhaving, in the present instance, an axial bore 22 extending the entirelength thereof, the lower section 22a defining a fuel chamber F and theupper section 22h defining a spring chamber C, a tip insert 24 mountedin the lower terminal end of the nozzle body having a valve seat 26 anda plurality of spray orifices 28 and a needle valve 30 mounted in thelower bore section 22a adapted for axial movement therein between aclosed position and an open position to permit pressurized fuel to bedischarged through the spray orifices 28. As illustrated the needlevalve 30 has a double tapered lower tip portion 32, the terminal end ofthe stem having a shape to conform to and snugly engage the valve seatin the closed position and the opposite upper terminal end of the needlevalve has a section of reduced diameter as at 34 adjacent the fuel inletport 36, the reduced section 34 terminating in a pointed conical pilotportion 38.

The needle valve 30 is normally biased to a closed position by means ofa compression spring housed in the spring chamber C between an upperspring seat 44 and a lower spring seat 46. The force of the compressionspring may be selectively varied to regulate the lfuel pressure at whichthe needle valve opens. In the present instance this is accomplished -bymeans of an externally threaded pressure screw which is threaded in theupper terminal end of the spring chamber C and has a head 52 to receivean adjusting tool such as a wrench so that it may be threaded inwardlyor outwardly thereby changing the compression of the spring. Theadjusting screw 50 has an axially extending groove 56 in its outersurface to provide fluid communication between the spring chamber C andthe leak-off line whereby fuel leakage into the springv chamber C may bevented to the leak-off line `and then to the main fuel supply.

The nozzle assembly further includes means to adjust the valve liftcomprising, in the present instance, a valve stop screw 60 having athreaded portion which engages internally of the pressure adjustingscrew 50 and has an elongated shank portion 62 of reduced cross sectiondepending from the threaded portion and spaced from the upper end of thelower spring seat 46 to provide a gap or spacing G therebetween. Thus,by simply adjusting the stop screw 60 axially, this gap G may be variedand thus the lift of the needle valve 30 also varied. The diameter D ofthe needle valve tip is smaller in cross section than the diameter D1 ofthe valve guide member tail section 34. By this arrangement, build up offuel pressure in the fuel chamber F results in axial movement of theneedle valve 30 upwardly against the bias of the compression spring toopen the valve and permit discharge of a measured quantity of fuelthrough the spray orifices.

In accordance with the present invention, the nozzle assembly includes avalve guide member which, -as illustrated, has an axial bore 72 thereinopen at its lower end with a circumferentially extending tapered inneredge 74 which seats on the conical inner tip portion 38 of the needlevalve 30 and a rounded head portion 76 which engages interiorly of aconical seat 78 in the lower face of the lower spring seat 46. The valveguide member 70 which is generally cylindrical and circular in crosssection is slidably fitted in a bushing 80 held in the lower end of thespring chamber by a shoulder 81 which may be formed by crimping orspinning after insertion of the bushing 80.

In nozzle assemblies it has been found that it is difcult to achieveperfect concentricity of the nozzle valve Seat and the needle valve tipto assure tight seating of the valve. If the valve tip is not tightlyseated in the closed position of the valve, fuel dripping resultsbetween injections causing carbon build up on the needle valve tip whichin turn results in poor engine combustion and excessive exhaust smoke.The present invention provides an arrangement which insures tightseating of the needle valve in the closed position even if the valveseat and valve are not precisely concentric. To this end the inner edge74 of the valve guide member 70 and the conical inner tip portion 38 ofthe needle valve 30 are made with a differential angle of taper.Preferably the angle of taper A of the inner edge 74 is a few degreesless than the angle of taper B of the conical inner tip portion 38 ofthe needle valve. Thus, in the present instance, even if the nozzle seatand valve guide are slightly misaligned, the needle valve 30 still seatstightly against the valve seat without binding the guide member 7 0 andthus minimizes sluggish valve action.

In some instances it has been found that the valve guide member willstick in an open position and the needle valve remains in a closedposition. In the past this resulted in over-fueling and excessive smokefor the reason that sticking of one nozzle assembly of a plurality ofnozzles operating from a single pump adversely affects the quantity offuel delivered to the remaining normally operating nozzle assemblies.

Another important feature of the present invention is the provision ofmeans for eliminating the over-fueling and excessive smoke conditionresulting when one nozzle assembly of a plurality sticks in a closedposition. To this end, the valve guide member '70 is provided with acontrol port connecting the spring chamber C and the axial bore 72, theaxial bore 72 and control port 90` in effect defining a by-passpassageway. In the normal operation of the valve, the fuel chamber F isthe high pressure side and the spring chamber, leak-off by-pass andleak-off manifold in the leak-off port are the low pressure side.Accordingly, in the present instance, the spring chamber C forms ineffect part of the leak-off system. The flow area of the control port90` is substantially equal to the total flow area of the spray orices 28so that in the event the needle valve 30 separates and assumes a closedposition, fuel pressure build up acting on the lower axial end face ofthe guide member 70 effects movement of the guide member upwardlyagainst the bias of the compression spring and permits the fuel chargeto be vented through the axial -bore 72 and control port 90V and throughthe remainder of the leak-off system. In this manner, the operation ofother fuel injection nozzles supplied from a common pump will not beadversely affected, that is, since the complete fuel charge for theinoperative nozzle is accommodated, the charge to the remainder of theoperative nozzles is not changed.

There is shown in FIG. 3 another embodiment of fuel injection nozzleassembly in accordance with the present invention which is generallydesignated by the numeral 100. The assembly includes an elongated nozzleholder 110, a fuel injection nozzle 112 mounted at the lower axial endof the holder by means of a cap nut 114, and a valve member 116 mountedin an axial bore in the nozzle.

The holder is an elongated, generally cylindrical member having a fuelinlet at its outer axial end (not shown) and an axial fuel passage 118communicating with the fuel inlet, an axial channel 120 providing a fuelleakoff which may be connected to a leak-off line (not shown) to conveyfuel leakage, for example, to t-he main fuel supply system. The lowerend of the channel 120 is enlarged as at 122 to define a spring chamberC. Housed in the spring chamber C is a compression spring 124 engagingbetween an upper spring seat 126 and a lower spring seat 128. The seats126 and 128 have projecting rod portions which are spaced apart todefine a gap G determining valve lift.

The nozzle 112 comprises a generally cylindrical body portion 130 and anelongated shank 132 of reduced cross section depending from the bodyportion defining a shoulder 134 which the lower end of the cap nutengages. The nozzle has an axial bore 136 which defines a fuel chamber Fwhich, as illustrated, is of a larger cross section than the largestcross section of the needle valve 116. The lower end of the fuel chamberF" tapers inwardly to define a conical seat 140 engageable by the tip142 of the needle Valve in the closed position to prevent fuel in thefuel chamber from being discharged through the spray orices 144 in thenose section 146. The Ibody portion has an angled fuel passageway 150which is maintained in alignment with the fuel passage 118 in the holderby means of a locating pin 160. Thus, in operation, fuel under highpressure delivered by a conventional fuel distribution pump passes tothe fuel chamber F through the passage 118 and passageway 150. Fuelpressure build up raises the needle valve 142 against the bias of thecompression spring 124 to permit a predetermined charge of the fuel tobe delivered through the spray orifices 144.

In accordance with this embodiment of the invention there is alsoprovided a valve guide member 162 of generally cylindrical shape whichengages in an axial opening 164 in the body portion of the nozzle, theguide member 162 having a rounded head portion 166 which engages in anarcuate seat 168 in the lower spring seat 128. The guide member has acentral axially extending bore 166 which is open at its lower end andwhich at its opposite end has a radial control port 170 communicatingwith the spring chamber C and the leak-olf passage 120'. In the presentinstance, the axial opening 164 in the body portion is enlarged as at165 to form an extension of the spring chamber C" providing fluidcommunication between the control port 170 and the leak-off system. Thiscontrol port 170 has substantially the same flow area as the total owarea of the spray orifices 144 so that in the event the Valve 116 sticksin a closed position, fuel pressure build up acting on the lower axialend face of the guide member will raise the guide member 162 upwardlyagainst the bias of the compression spring and permit the predeterminedfuel charge to be vented to the low pressure side of the valve, that isthrough the spring chamber C" and leak-E bypass. In this manner, theoperation of other fuel injection nozzles being supplied from a commonpump will not be adversely affected as discussed previously in greaterdetail.

In accordance with this embodiment of the invention, the lower edge 176of the guide member is tapered and the inner terminal end of the needlevalve is provided with a conical head 178, the head 178 preferablyhaving an included angle of taper A" greater than the angle of taper B"of the inner edge 176 of the guide member. The differential between theangles of taper A and B is preferably a few degrees. This arrangementinsures tight seating of the needle valve against the seat even if thebore for the guide member is not precisely concentric with the seat 140.Furthermore, this mating arrangement insures tight seating of the needlevalve even if a difference in concentricity develops in the nozzleassembly due to warpage, for example, over a period of use.

While particular embodiments of the present invention have beenillustrated and described herein, it is to be understood that changesand modifications may be made herein within the scope of the followingclaims.

I claim:

1. A fuel injection nozzle assembly comprising an elongated body havingan axial bore including an upper bore section defining a leak-offchamber and a lower bore section therein, means defining a valve seat atone axial end of the body and at least one spray orifice, a valve memberhaving a needle mounted for axial movement in said lower bore sectionbetween a closed position wherein the valve member needle engages saidseat and an open posi tion spaced from said seat to permit discharge offuel through said spray orifice, `a valve guide member mountedinteriorly of said body and normally adapted for movement with saidvalve member, said valve guide member having a bypass passageway thereinwith an outlet port communicating with said leak-off chamber of thevalve,

said outlet port having a flow area substantially equal to the liow areaof the spray orifice.

2. A fuel injection nozzle assembly as claimed in claim 1 wherein theterminal end of the said needle valve opposite said tip is provided witha conical head and the valve guide member is provided with acircumferentially extending tapered edge at its lower end which seats onsaid conical head, the taper of said conical head and said lower edge ofthe valve guide member being different.

3. A fuel injection nozzle assembly as claimed in claim 2 wherein theincluded angle of taper of said conical head of the needle valve memberis a few degrees greater than the included angle of taper of the loweredge of said guide member.

4. A fuel injection nozzle assembly as claimed in claim 1 including abushing mounted in said body having an axial bore within which the guidemember is mounted for axial movement.

5. A fuel injection nozzle assembly as claimed in claim 1 including atip insert mounted in the lower end of the body.

`6. A fuel injection nozzle assembly as claimed in claim 1 includingbiasing means engaging said guide member to normally maintain the valve,member in a seated position.

7. A fuel injection nozzle assembly as claimed in claim 6 wherein saidbiasing means comprises a compression spring mounted between upper andlower spring seats and including selectively adjustable means forcontrolling valve lift.

8. A fuel injection nozzle assembly as claimed in claim 7 including apressure adjusting screw member mounted in the upper axial end of thebody abutting said upper spring seat and which may be actuated axiallyof the body to vary the biasing force of the compression spring.

9. A fuel injection nozzle assembly as claimed in claim 8 wherein saidadjusting screw member has an axially extending lgroove to permit fuelleak off from the spring chamber.

10. A fuel injection nozzle assembly comprising a holder having aleak-off chamber therein, a nozzle having an -axial bo-re mounted at oneaxial end of the holder, said nozzle comprising a body portion and anelongated shank of reduced cross section depending from the body portionhaving a valve seat at` its outer terminal end and at least one sprayorifice, a valve member mounted in said bore, a valve guide membermounted in said body portion and normally adapted for movement with saidvalve member, biasing means normally urging said valve member to aclosed position, said valve guide member having a bypass passagewaytherein with an outlet port communicating with said leak-off chamber,said outlet port having a flow area substantially equal to the liow areaof the spray orifice.

11. A fuel injection nozzle assembly as claimed in clairn 10 whereinsaid axial bore in the nozzle is enlarged adjacent the leak-off chamberin said holder to provide fluid communication between the outlet portand said leak-off chamber in all positions of said valve member.

References Cited UNITED STATES PATENTS 403,264 12/ 1933 Great Britain.

EVERE'IT W. KIRBY, Primary Examiner.

U.S. Cl. X.R. 239-453, 584

